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Yamaha Grizzly 660 Exhaust | HMF Performance Series

  • Yamaha Grizzly 660 Exhaust | HMF Performance Series
  • Yamaha Grizzly 660 Exhaust | HMF Performance Series
  • Yamaha Grizzly 660 Exhaust | HMF Performance Series
  • Yamaha Grizzly 660 Exhaust | HMF Performance Series

Yamaha® Grizzly 660

The Yamaha Grizzly 660 system is available as a Slip-On or Full System in the Performance and Titan series.  Depending on the series, the slip-on system picks up 10-15% more horse power and torque throughout the power curve, and the Full System picks up 15-25% more.  No matter which series, the HMF exhausts weight substantially less that the stock exhaust.

Fuel tuning is required learn more

Fuel Tuning is absolutely required when installing an HMF Exhaust on this machine. Failure to tune the engine can cause excessive damage to the exhaust system and engine, while voiding the warranty on your exhaust and possibly on your machine. (check with local dealer). See the tuning settings below for the proper fuel tuning solution on your machine.

Exhaust Systems

Yamaha® Grizzly 660 ATV Accessories

Tuning

Recommended Tuning
Slip On - 175 Mikuni small 
Full System - 180 Mikuni small 

Free flowing air box may require 185-190 Mikuni small 

HMF Basic Jet Kit Includes
170, 175, 180, 185, 190 Mikuni small 

Low Speed Fuel

Going down on the number scale will reduce low speed fuel. Going up on the number scale will increase low speed fuel.

Mid Range Fuel

Going down on the number scale will reduce mid range fuel. Going up on the number scale will increase mid range fuel.

High End Fuel

Going down on the number scale will reduce high end fuel. Going up on the number scale will increase high end fuel.

Green Lower Switch Point

Going down on the number scale will turn green mode on earlier. Going up on the number scale will turn green mode on later. These modes typically will not need adjusted from their base setting.

Yellow Lower Switch Point

Going down on the number scale will turn yellow mode on earlier. Going up on the number scale will turn yellow mode on later. These modes typically will not need adjusted from their base setting.

Red Lower Switch Point

Going down on the number scale will turn red mode on earlier. Going up on the number scale will turn red mode on later. These modes typically will not need adjusted from their base setting.

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